Aero-acoustic cavity

Application Challenge 1-01 © copyright ERCOFTAC 2004

Overview of Tests

The experimental conditions are described in TR-026-20.pdf. The full range of tests covers a variety of free-stream Mach numbers between 0.4 and 1.35, and for two cavity configurations, so-called shallow and deep. We concentrate here on a single one of these, namely M=0.85 deep cavity.

Unsteady pressure measurements were recorded by 10 Kulite transducers along the centreline of the rig (which did not coincide with the centreline of the cavity itself), at a sampling rate of 6000Hz. The position of each transducer is given in Table 1.

Table 1 Kulite Transducer Positions
Transducer Number	Distance X from leading edge of cavity (mm)
1	25.4
2	76.2
3	127.0
4	177.8
5	228.6
6	279.4
7	330.2
8	381.0
9	431.8
10	482.6

M219D085.dat for the 10 transducer locations are stored using a sampling frequency of 6000 per second, for a total duration of just over 3.4 seconds. The M219DRMS.dat at these locations are also presented.

There is no independent verification of the validity/accuracy of the experimental data.

Test Conditions

Measurements have been performed on a range of free-stream Mach number, (empty) cavity depths, with and without doors at 90o open (Media:TR-026-20.pdf reports on the latter only). If appropriate, during the duration of the QNET project, a matrix of alternative test conditions against which to benchmark CFD calculations will be provided.

The specific test case of interest is classed as a deep cavity (L/D = 5) without doors, with flow conditions as follows:

M = 0.85

Re = 6.84e6 (based on cavity length of 0.508m)

P₀ = 99612.06 Pa

P = 62059.14 Pa

T₀ = 305.06 K

Incidence = 0o

References

TR-026-20.pdf Henshaw M.J de C., “M219 Cavity case in Verification and Validation Data for Computational Unsteady Aerodynamics”, RTO-TR-26, AC/323(AVT)TP/19, October 2000

Contributors: Fred Mendonca; Richard Allen - Computational Dynamics Ltd

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